A combine harvester is a machine that is used to harvest grain crops. The objective is to complete several processes, which traditionally were distinct, in one pass of the machine over a particular part of the field. Among the crops that may be harvested with a combine are wheat, oats, rye, barley, corn, soybeans, flax or linseed, and others. The waste (e.g., straw) discharged on the field includes the remaining dried stems and leaves of the crop which may be, for example, chopped and spread on the field as residue or baled for feed and bedding for livestock.
A combine harvester cuts crop using a wide cutting header. The cut crop may be picked up and fed into the threshing and separating mechanism of the combine, typically consisting of a rotating threshing rotor or cylinder to which grooved steel bars commonly referred to as rasp bars or threshing elements may be bolted. These rasp bars thresh and aid in separating the grains from the chaff and straw through the action of the drum against the concaves, i.e., shaped “half drum,” that may also be fitted with steel bars and a meshed grill, through which grain, chaff and smaller debris may fall, whereas the straw, being too big or long, is carried through to the outlet. The chaff, straw, and other undesired material are returned to the field via a spreader mechanism.
In an axial flow combine, this threshing and separating system serves a primary separation function. The harvested crop is threshed and separated as it is conveyed between a longitudinally arranged rotor and the inner surface of an associated chamber comprising threshing and separating concaves, and a rotor cage or cover. The cut crop material spirals and is conveyed along a helical path along the inner surface of the chamber until substantially only larger residue remains. When the residue reaches the end of the threshing drum, it is expelled out of the rear of the combine. Meanwhile, the grain, chaff, and other small debris fall through the concaves and grates onto a cleaning device or shoe. For ease of reference, this smaller particulate crop material that contains the grain and chaff is referred to as threshed crop. The grain still needs to be further separated from the chaff by way of a winnowing process.
Clean grain is separated out of the threshed crop by way of a flat oscillating cleaning system that can include a combination of oscillating screens (sieves), a fan which blows air through/above/beneath the sieves, and some mechanism which transports the material to be cleaned from beneath the threshing system to the sieves. Clean grain that is separated from residue via the sieves is typically transported to a grain tank in the combine for temporary storage. The grain tank is typically located atop the combine and loaded via a conveyer that carries clean grain collected in the cleaning system to the grain tank. The grain may then be unloaded through a conveying system to a support trailer or vehicle, allowing large quantities of grain to be unloaded in the field without needing to stop harvesting when the grain tank fills.
The cleaning system of a combine swings on arms which are coupled to the cleaning system at one end and coupled to the combine chassis at another end. Accordingly, as the cleaning system swings back and forth, the cleaning system moves in an arc having a fore/aft direction with some up-down direction. Presently, combines may be equipped with hillside compensation mechanisms (e.g., side-shaking mechanisms) for combine cleaning systems which provide compensation to the cleaning system when the combine experiences a change in inclination (i.e., harvesting on uneven terrain). On inclined ground, the side-shaking mechanisms introduce an additional side-to-side direction in the shake geometry of a sieve, causing material to resist its natural tendency to migrate to the lower side of the sieve and remain more evenly distributed across the width of the sieve.
These conventional side-shaking mechanisms are configured to move freely in the fore-aft direction and the side-to-side direction. Movement in the up-down, however, causes stress to side-shaking mechanisms, undesirably affecting the overall motion of the cleaning system. To compensate for some of the stress, some side-shaking mechanisms are configured to physically bend in the up-down direction or have elements, such as rubber bushings or ball joints, to allow some movement in the up-down direction. These conventional compensation approaches, however, make the cleaning system harder to move, causing the cleaning system motion to be less smooth and perform less efficiently. Further, stress is still present with the conventional compensation approaches, affecting the overall performance and operational life of the cleaning system. What is needed is an improved side-shaking assembly for a combine cleaning system.